Patients were excluded from the study if they had one or more of the following characteristics: Born preterm ≤34 weeks gestation, previous history of wheezing, steroid use within 48 hours of presentation, obtundation and progressive respiratory failure requiring ICU admission, history of apnea with in 24 hours before presentation, oxygen saturation ≤ 85% on room air at the time of recruitment, history of a diagnosis of chronic lung disease, congenital heart disease, or immunodeficiency.